The whole region crossed by the sea road is desert of the most difficult and forbidding character. By this road all the great invasions--the Roman, Egyptian, Assyrian, Greek, and French--have been made. The road enters the desert at El Arish and from there to El Kantara on the Suez Canal, the probable point of attack of an army moving by this route, is 100 miles. Over this whole distance there are only three places, once an army has left El Arish, where water can be had. The first is a matter of a day's march, at El Maza, thirty mile away; the second is at Bir-El-Abd, another day's march; and the third at Katieh, within striking distance of the canal. Without the construction of a special railway the transport of a force large enough to efficiently control the canal by this route seems to be out of the question. The southern route, known as the Hadj, or Pilgrim's Road, running from Akaba to Suez, besides being longer is even worse off in the matter of water. This was the traditional path of pilgrims traveling from Egypt to Mecca, and still is much in use for that purpose. Something like 150 miles separate Akaba and Suez, yet only two watering places are to be found in the whole distance. The first is three days' march from the former place, at a point called Nakhl, where modern cisterns had been built and an adequate supply of water for a large force probably was obtainable. The next watering place is another three days' march, at Ayun Mousa, or Well of Moses, within a short distance of the canal. But tremendous as were the problems facing a considerable body of men in attempting to cross the Sinai desert and arrive at the Suez Canal in condition to fight a strong, fresh and fully prepared foe, they were not to be compared to the difficulties that would face such an army when the canal had been reached. We have seen how great an obstacle a wide river, such as the Vistula, proved to be to an army when attempting to cross in the face of a prepared enemy. In the case of the Suez Canal, although there were no strong currents, a force attempting to cross it had to contend with two added difficulties: The Suez Canal could not, in the circumstances be turned, as was the Vistula by the Germans. Furthermore its defensive value was immeasurably increased by the circumstance that it could and did carry warships of the largest type which not only had the value of fortresses mounting the heaviest of guns, but were mobile as well. And finally, because of the nature of the shores of the canal, it was possible for an attacking force to cross it at but few points.